An electronic lock using commercial power or batteries, which is directly connected with the circuit in the lock body to supply power, is called an “active electronic lock”. Traditional active electronic locks (adopting IC card, ID card, fingerprint identification and the like) that are widely used at present need 4 to 6 pieces of batteries of size AA or LR6, and the service life of the batteries is usually 3 to 12 months. Therefore, the active electronic lock not only consumes a large number of batteries, but also requires more maintenance work, such as frequent inspection, battery replacement and the like. Furthermore, the batteries may be in loose contact such that electronic elements and devices become aged from being energized for long, influencing the reliability and service life of the active electronic lock. On the other hand, electronic locks making use of commercial power for power supply have disadvantages of a limited application range, high power consumption in standby state all the year round, inconvenient installation, increased maintenance, and adverse effects on protection of the environment.
In 1999, the patent ZL 99203695.X Key to Electronic Lock disclosed a technical solution of a basic active “key to electronic lock”. The key comprises an IC chip for producing an unlocking password, and the working batteries of an electronic lock are further arranged in the electronic key. Based on this patented technology, the applicant combined the patented technological packages ZL 99207205.0 Electronic Locating Device of Electric Controlled Lock and ZL 99202022.0 Trip Device of Electric Lock (with a WIPO patent number of WO 0042278, an American patent number of U.S. Pat. No. 6,502,870, an European patent number of EP 1 167 663 and an Australian patent number of AU 752034B), and developed a series of low-power passive electronic locks using the active key to electronic lock. The passive electronic lock has the advantages of easy installation, easy use, low power consumption, protection of the environment, better reliability and much longer service life than that of the active electronic lock. However, the above-mentioned patented technological packages cannot be used for to develop a passive electronic lock cylinder that is as small as a common mechanical lock cylinder to directly substitute or replace the mechanical lock cylinder.
In 2000, American U.S. Pat. No. 6,615,625 Electronic Locking System, with Chinese patent numbers of ZL 01804076.4 and ZL 200710108769.5, disclosed a passive electronic lock cylinder which used the technology of an active key to electronic lock and was of comparative size to that of the common mechanical lock cylinder, and this passive electronic lock cylinder was made commercially available.
However, the locking system of American U.S. Pat. No. 6,615,625 has the following disadvantages:
1. The passive electronic lock cylinder uses a linear solenoid as an executive element, and the plunger (a displacement limiting armature for locking and unlocking) of the linear solenoid does not have locating and self-locking functions after power-off (namely that the plunger is automatically restored by a compression spring as soon as power is switched off). The linear electromagnetic solenoid must therefore be energized to attract the plunger. The power-on time for unlocking (namely the waiting time for rotating a lock plug to a specified angle via the key) is about 1 second; resulting in increased electric energy being consumed during this time, and the electromechanical conversion efficiency of the passive electronic lock cylinder is low. A battery with relatively large volume and capacity must be installed in the active electronic key to provide for extended use over time, making the size of the active electronic key relatively large.
2. The plunger does not have a self-locking function after power-off, so that the rotation angle of the lock plug cannot be more than 360 degrees (by comparison the lock plug of a common lock cylinder for an anti-theft door is required to rotate more than 720 degrees). If the lock plug is required to rotate several times, it consumes substantially more electric energy, decreasing the usefulness and commercial viability of the lock.
3. The microcontroller unit (MCU) in the electronic control circuit of the lock plug cannot distinguish between the dynamic and static mechanical positions of the pin and plunger in the lock plug, and therefore cannot distinguish between the locking and unlocking states of the lock cylinder. Therefore, the passive electronic lock cylinder cannot be adapted to perform remote monitoring functions and the like, or functions requiring higher intellectualization and higher safety through wired/wireless networks.
In 2004, patent ZL 200410037420.3 Intellectual Passive Electronic Lock Cylinder disclosed a passive electronic lock cylinder adopting the technology of the active key to electronic lock. The cylinder of the intellectual passive electronic lock disclosed has the disadvantages of: being unable to distinguish between the dynamic and static positions of mechanical actuating elements due to the adoption of the linear electromagnetic solenoid (electromagnet) as an executive element. Furthermore, the intellectual passive electronic lock cylinder also has the three disadvantages of the patent ZL 01804076.4; in that there is no disclosure of measures taken to prevent unexpected unlocking caused by the impact of external force, so that when exerting an impact force on the lock cylinder, a driving rack will move axially, under inertia engaging with a driven rack. Thus, the intellectual passive electronic lock cylinder described can easily be unlocked by hitting with a hammer or a weight.